Gypsum

Application of gypsum is an important tool for managing high soil sodium levels. But some of you who think they are buying gypsum may in fact be purchasing a different, and much less effective product.

The problem stems from the recent commercialization of several products based on a material known as calcium sulfate anhydrite (also known as mined anhydrite; the chemical formula is CaSO₄). This material is not readily soluble in water, and therefore would not be very effective at…